The present utility model relates to the field of power-driven tools, in particular to a novel method in which the three-step speed change, two-stage planetary gear speed reduction are used in the gear box to make the power-driven tool acquire three kinds of transmission ratio outputs.
At present, there are mainly two kinds of speed regulation for the power-driven tool: one relies on speed regulation switch to regulate speed but it reduces rotary speed at the cost of losing torque; the other relies on gear box to reduce speed but it has the choice of only two speeds.
The object of the present utility model is to solve the problem that the power-driven tools relying on gear box can have only two speed transmission. However, this three-speed gear shifting box can make power-driven tools acquire large torque, low rotary speed output and multiple rotary speed choices, being suitable for processing different material.
In order to achieve the above-mentioned objects, the technical scheme adopted is: a triple gear is fitted on the electric motor output shaft of a conventional power-driven tool. Three sets of planetary gears are sleeved respectively on an intermediate gear disk and are meshed respectively with the corresponding triple gear and three internal gears. A poking spring makes an internal gear regulating ring move, and fixes one of the internal gears. The gears on the intermediate gear disk mesh with planetary gears on four planetary gear shafts on a main shaft, and then again planetary gears also mesh with the fixed internal gear.
The present utility model is a combination of two sets of planetary gear which increases the function of large torque and low rotary speed output and simultaneously fixes respectively the internal gear to make gear box increase the function of multiple rotary speed choices and also make the integral structure of the gear box compact.